Unborn has a hole in his head in US

Has anyone dealt with to where the doctor discovered a hole in your baby’s head , but then they don’t have a clue what it is? I’m 20 weeks. I have to go back for a MRI in 5 weeks for a better view of my baby. If the hole doesn’t close up… will it cause problems to my baby in the future? I will hate to terminate my baby as they mentioned💔💔💔